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Discussion Starter #1 (Edited)
I previously had a misfire on cylinder 3 and 4, p0309,p0303, p0304. There was oil on the spark plugs and coil boots. I replaced the spark tube seals and the valve cover gasket and is no longer leaking into spark plug wells and have also repulled spark plugs to confirm no oil on the new plugs.

Howevever, currently still have a persistent Cylinder 3 and 4 Misfire (flashing engine light as well) and clicking noise when accelerating when around 2000-2500 RPMs. I have switched around the plugs and coils and the problem does not change and same codes after reset. Engine is running rough. I also replaced the ECV valve as that was stuck open and could blow air through it. I changed the PCV valve as well. No change at all.

*Short Term Fuel Trim - 0%
*Long Term Fuel Trim - 3%

*O2 sensor 1 before throttle: 0.450, After throttle: 0.850.
*02 sensor 2 stays around 0.470


Any help or guidance would be very much appreciated.

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I previously had a misfire on cylinder 3 and 4, p0309,p0303, p0304. There was oil on the spark plugs and coil boots. I replaced the spark tube seals and the valve cover gasket and is no longer leaking into spark plug wells and have also repulled spark plugs to confirm no oil on the new plugs.

Howevever, currently still have a persistent Cylinder 3 and 4 Misfire (flashing engine light as well) and clicking noise when accelerating when around 2000-2500 RPMs. I have switched around the plugs and coils and the problem does not change and same codes after reset. Engine is running rough. I also replaced the ECV valve as that was stuck open and could blow air through it. I changed the PCV valve as well. No change at all.

*Short Term Fuel Trim - 0%
*Long Term Fuel Trim - 3%

*O2 sensor 1 before throttle: 0.450, After throttle: 0.850.
*02 sensor 2 stays around 0.470


Any help or guidance would be very much appreciated.

Sent from my SM-G950U using Tapatalk
O2 sensor and fuel trim data seems pretty normal to me.

This could be the crank sensor, have you checked that?

P0309 isnt possible unless you are v10 or v12 swapped.
Others point to coil failure. Probably from the oil.
Guessing he meant to write P0300.
 

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Testing procedures and details of your O2

COIL RESISTANCE: 0.75 ohm +- 15%
If you have done more than 60k on them its time to replace anyways. Coils ARE a wear item. They, like brake pads can wear out but still function. Same with electric motors. Electricity can cause wire windings to actually move/vibrate (Motor buzz or transformer buzz).
 

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If you have swapped the coils on the misfiring cyls to the cyls that are not misfiring and that hasn't changed anything I think that rules the coils out as the cause of the misfire. I doubt replacing them will help much.

Is there any difference in the colour of the misfiring plugs to the other two? Are the misfiring plus wet when removed?
Have you compared the strength of the spark on the Cyl 3 & 4 coils to the other two?
Have you done a compression test?

If I helped you fix it, why not...

Your support is greatly appreciated
 

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If you have swapped the coils on the misfiring cyls to the cyls that are not misfiring and that hasn't changed anything I think that rules the coils out as the cause of the misfire. I doubt replacing them will help much.

If I helped you fix it, why not...

Your support is greatly appreciated
This is false. Our engines do not have a signal return to ecm to verify spark occured. Those are 3 or 4 wire depending on features. Ours are two wire,ECM Dwel controlled. Swapping them will still throw codes and run rough. However while running unplugging and replugging them and listening for strong or weak changes is a method. Your method for checking color if spark is a good method as well; improved upon only by one of the screwable ones to calculate voltage over distance.
 

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This is false.
Eh, no it's not. But don't take my word for it. Use the advanced search facility and see how many misfires on the forum are diagnosed using that method.

kylemarshall said:
Swapping them will still throw codes and run rough.
Well, of course. But if you have a P0303 code logged because the coil is faulty, moving that coil to cylinder 2 will result in P0302. The OP still got P0303 after moving the coil, meaning the coil is not the cause of the cyl 3 misfire. Why replace the coil if that is not the cause of his complaint?

If I helped you fix it, why not...

Your support is greatly appreciated
 

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Eh, no it's not. But don't take my word for it. Use the advanced search facility and see how many misfires on the forum are diagnosed using that method.


Well, of course. But if you have a P0303 code logged because the coil is faulty, moving that coil to cylinder 2 will result in P0302. The OP still got P0303 after moving the coil, meaning the coil is not the cause of the cyl 3 misfire. Why replace the coil if that is not the cause of his complaint?

If I helped you fix it, why not...

Your support is greatly appreciated
The only time the code will change place is if their is a circuit fault on that coil. As stated before we do not have a sense line to the ecm. These are 2 wire coils....

So though your test will work with fully faulty coils, it may not work with worn coils.

The codes provided are its guess of which cylinders are a fault with the information it can gather. Though very accurate, it can be wrong.

All i mean by this is simply unplugging one at a time is the most accurate method. As well as I had only said replace them if he hasnt within 60k kms yet because that is just general maintence and engine functioning perfectly or not, should be done. I never said "replace them all, thats your problem"
Sorry for the confusion.
 
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